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Page 21
measurement can take a very long
time. The keys F2 and F3 can step
the baudrate up or down.
The baudrate adjustment via keys F2
or F3 is also important for simplex
ARQ signals, which often can not be
measured. With preselection of the
IAS-BAUDRATE, simplex ARQ signals
can be measured (SITOR-ARQ, SI-ARQ,
SWED-ARQ, DUP-ARQ).
Measurements to 1/1000 Baud can be
false due to differences in the
quartz oscillators. These false
measurement can be compensated and
corrected using a CONSTANT. The
best calibration reference is the
FEC-A long wave signal. Measure
this signal for 10 minutes with
IAS-BAUDRATE. Now use the Key BU-ZI
to adjust the QFC-FACTOR (abt. 10
to 40) as close possible to 96.0000
Baud. The key BU-ZI has a repeat
function.
Multiple Scroll Inhibit (MSI)
Eliminates multiple scrolls (line
feeds) on the screen and printer. A
paper and screen space saving
device when the sending station
sends more than one. Press the
appropriate keys BU-ZI and F2 to
indicate MSI ON or MSI OFF on
status line.
character. Press the appropriate
keys BU-ZI and F1 to indicate UOS
ON or UOS OFF on status line.
Unshift on Space (UOS)
When "on" the Unshift on Space
causes
the
data
output
to
automatically shift to "Letters"
case upon receipt of a "space"
Video display 40x18 and 80x24 lines
Each press of BU-ZI and F4 buttons
changes from one video mode to the
other.
F1
F2
SPEED CHECK
BAUDRATE SELECTOR
F3
MODE RECALL
F4
F4+F3
FORWARD SEQUENCE
REVERSE SEQUENCE
After choosing ARQ-E, the Baud rate
is set to the default of 96 Baud,
however this can be changed with
function key F2. The Baud rate
measured by using function key F1
remains stored (for all modes)
until
a
new
measurem ent
is
performed. After the decoder has
synchronized to the ARQ-E signal it
displays the repetition cycle (4 or
8) which gives clues concerning the
same radio net. The function key F3
should
be
pushed
after
every
station or frequency change.
The synchronous full-duplex singlechannel ARQ (automated request) has
Polarity Display
Press the appropriate keys BU-ZI
and
F3
indicates
NOR
or
INV
polarity on status line if the
microprocessor is synchronized.
Displays the baud rate
Selects standard or variable Baud
rates(as obtained from the F1
measurement)
Redisplay of the mode as well as resynchronization
go to next operating mode
go to previous operating mode
become an important communications
mode. Single-channel ARQ uses a
parity
check
to
recognize
transmission errors. The procedure
is that the receiver returns a
question mark to the transmitter
for
each
detected
error.
The
transmitter then re-transmits the
last 3 or 7 characters which it
precedes with a question mark. To
keep the 2 stations synchronized,
both stations transmit carrier and
information continuously. If there
is no information, then a bit
pattern (Idle character) is used
for modulation.